Action Potential and Synapses Flashcards

60 vocabulary flashcards covering the anatomy of neurons, action potential signaling, types of synapses, and neurotransmitters based on lecture notes.

Neuron

Nerve cells found throughout the body that are mostly made by birth and are the longest living cells in the body.

Parkinson’s, Huntington’s, and/or Alzheimer’s diseases

Diseases which result in nerve cell death

White matter

The axons that run from the brain down the spinal cord, and are also found within the brain.

Grey matter

The neuronal cell bodies found in the brain and spinal cord.

10-100 A

Distance between terminal and receptor

Schwann cells

Cells responsible for creating the insulation around the axon.

Myelin sheath

An axon insulation layer created by sphingomyelin, a type of sphingolipid.

Sphingomyelin

A sphingolipid used to create the myelin sheath; its absence can lead to conditions like spina bifida or multiple sclerosis.

Craniorachischisis

A neural tube defect involving a completely open brain and spinal cord.

Anencephaly

A condition characterized by an open brain and a lack of skull vault.

Encephalocele

The herniation of the meninges and brain through a defect.

Iniencephaly

A defect involving the occipital skull and spine with extreme retroflexion of the head.

Spina bifida occulta

A closed, asymptomatic neural tube defect where some vertebrae are not completely closed.

Closed spinal dysraphism

Deficiency of at least two vertebral arches covered by lipoma

Meningocele

A protrusion of the meninges filled with CSF through a defect in the skull or spine.

Myelomeningocele

An open spinal cord accompanied by a meningeal cyst.

Afferent

Sensory signals traveling toward the brain.

Baroreceptors

Receptors responsible for monitoring pressure.

Nociceptors

Receptors responsible for monitoring pain.

Efferent

Motor signals traveling from the brain to the rest of the body.

Somatic

The voluntary part of the efferent system that controls skeletal muscles.

Autonomic

The involuntary part of the efferent system that controls smooth muscles.

Sympathetic

The division of the autonomic nervous system responsible for the 'fight or flight' response.

Parasympathetic

The division of the autonomic nervous system responsible for 'resting and digesting'.

Sodium

Found in extracellular fluid

Potassium

Found within the cell

Leak gates

Channels that allow simple diffusion of Na+ in and K+ out to help establish concentration gradients.

Na+/K+ ATPase pump

A primary active transport pump that actively transports $3 \text{ Na}^+$ out of the cell for every $2 \text{ K}^+$ transported in to prevent equilibrium.

Resting Membrane Potential (RMP)

The stable electrical potential of a neuron at rest, typically maintained at -70 mV

Graded Response

A process where a ligand binds to regulated gates, causing $Na^+$ to diffuse into the neuron and push $K^+$ toward the axon hillock.

Ligand regulated gates (LRG)

Gates that open when a ligand binds to them, allowing only $Na^+$ to diffuse through.

Trigger voltage

The specific voltage level of $-50 \text{ mV}$ at the axon hillock required to initiate an action potential achieved by the accumulation of K+.

Action Potential

A signal involve voltage regulated gates (VRG) found from the axon hillock to the telodendrion.

Positive Feedback

The response of voltage regulated gates when Na+ is allowed into the cell

Depolarization

The reversing of poles from $-50 \text{ mV}$ to $+30 \text{ mV}$ caused by $Na^+$ diffusing into the cell.

-50 mV

The voltage the triggers an action potential and allows VRG to open.

30 mV

The voltage at which Na+ VRG close and K+ VRG open

-70 mV

The voltage at which K+ VRG begin to close.

-90 mV

The voltage at which Na+/K+ ATPase pump actively transport Na+ and K+ to reestablish RMP

Repolarization

The drop in voltage from $+30 \text{ mV}$ to $-70 \text{ mV}$ as $K^+$ gates open and $K^+$ diffuses out.

Hyperpolarization

The drop in voltage from $-70 \text{ mV}$ to $-90 \text{ mV}$ before the RMP is reestablished.

Terminal boutons

The distal ends of telodendria containing vesicles filled with neurotransmitters.

Calcium VRG

Channels at the terminal boutons that open at -50 mV to allow Ca²+ to diffuse into the cell.

Exocytosis

The release of neurotransmitters from vesicles into the synaptic cleft, activated by Ca²+.

Phagocytosis

One of the three methods for the removal of neurotransmitters from the synaptic cleft.

Reuptake

A method of neurotransmitter removal from the synaptic cleft using a specific pump.

Enzymatic degradation

One of the three way to remove neurotransmitters from the synaptic cleft using Ach esterase

Electrical Synapses

Communication between neurons via gap junctions.

Chemical Synapses

Communication between neurons through the release of transmitter substances.

One-way conduction

The characteristic of neuronal communication where signals are always transmitted in a single direction.

Neuropeptides

Potent transmitters made of small chain amino acids that cause prolonged actions, such as endorphins or enkephalins which typically attach to G protein-coupled receptors

Endorphins

Neuropeptides that relieve pain or stress, help mood, and are associated with pleasure like laughter or love.

Enkephalins

Powerful pain killers found in the brain, spinal cord, and adrenal medulla that bind to opioid receptors.

Vasoactive intestinal polypeptide (VIP)

A neuropeptide that regulates digestion, smooth muscles, the immune system, and hormonal release.

TRH

Thyrotropin-releasing hormone, which regulates thyroid gland activity.

CRH

Corticotropin releasing hormone, which activates ACTH to stimulate the release of glucocorticoids.

GnRH

Gonadotropin releasing hormone; regulates reproduction

GABA

A small molecule from the posterior pituitary, rapidly acting transmitter that is inhibitory.

Glutamate

A small molecule from the posterior pituitary, rapidly acting transmitter that is excitatory.

Presynaptic terminal

The part of the neuron that contains transmitter vesicles and mitochondria to provide energy for synthesis of neurotransmitter.

Ionophore component

The part of a postsynaptic receptor that extends through the membrane and either opens an ion channel or activates a second messenger system.

Binding component

The part of a postsynaptic receptor that extends into the synaptic cleft to bind with the transmitter.

Ionotropic receptor

A receptor that functions as a ligand-gated ion channel for rapid activation or inhibition.

Cation channels

Channels that allow sodium (and sometimes potassium or calcium) to pass, exciting the postsynaptic neuron.

Anion channels

Channels that allow chloride to pass, inhibiting the postsynaptic neuron.

Second Messenger Activators (SMAs)

Activators, often G-protein coupled, that cause prolonged changes in neuronal activity such as those required for memory.

cAMP

Cyclic adenosine monophosphate, a common molecule in second messenger systems that stimulates metabolic machinery.

Fatigue

A protective mechanism against excess activity caused by the exhaustion of transmitter stores in synaptic terminals.

Post-tetanic facilitation

Enhanced responsiveness following repetitive stimulation caused by a build-up of calcium ions in presynaptic terminals.

Synaptic delay

The time it takes for neurotransmission to occur, which can be used to calculate the number of neurons in a circuit.

Acidosis

A condition that depresses neuronal activity; a pH change from 7.4 to 7.0 usually induces coma.

Alkalosis

A condition that increases neuronal excitability; a pH change from 7.4 to 8.0 usually induces seizures.

Hypoxia

Interruption of blood flor to the brain for 3-7 seconds which can lead to unconsciousness